CY545 Stepper System Controller
www.ControlChips.com
The Number command specifies the number of steps the CY545 is to take in the relative step
mode. It uses a 24-bit parameter, so the CY545 can travel + or - 16 million steps from its current
position in the relative mode. No stepping occurs when the Number command is issued, the
command simply defines the number of steps to take, and this value is stored in an internal N
register of the CY545.
The + command selects the clockwise direction for stepping. This command causes the CCW
signal to go low.
The - command selects the counter-clockwise direction for stepping. The CCW signal will go
high when this command is used. Also, stepping direction may be controlled externally, by
driving the CCW pin with the desired level. If this function is used, the - command should be
issued, so the CCW signal is high. It can then be pulled low externally to force clockwise
stepping.
If the CCW pin is being driven low by the CY545, it is a stronger sink device, and will require a
very strong external signal to force the pin into the high state for CCW stepping. However, if the
CCW pin is held high by the CY545, from a - command, it can easily be driven low for CW
stepping.
Set Step Mode
Two CY545 commands control step operation modes for the CY545. They are:
A Pos24
C
Set current step position
Select continuous step mode
The At command sets the current position kept by the CY545 to the value of its parameter. This
number is a 24-bit value, so any position from 0 to 16777215 may be specified. Normally, this
command is used after stepping to a known mechanical position, such as a “home” position
sensor, and can calibrate the CY545 to make this position always be the same number.
While the CY545 is stepping, the internal current position is always updated. The position is
incremented during CW stepping, and decremented during CCW stepping. You may query the
CY545 for its current position while it is not stepping.
The position value is not too important for relative mode stepping, in which the direction and
number of steps are specified. However, it is very important for absolute mode stepping, in
which a target position is specified, and the CY545 computes the direction and number of steps
required to reach the target.
The Continuous command sets a special step mode in the CY545. In this mode, the CY545 will
accelerate from the initial rate to the final rate, and then run continuously. It will not ramp down
or stop at any particular position or number of steps.
In order to stop a continuous motion, the INHIBIT-ABORT signal must be pulled low, forcing the
CY545 into a deceleration mode, and then be kept low to stop the CY545. The CY545 will stop,
after it has decelerated to the starting rate, if the INHIBIT _ABORT signal is still low.
The continuous mode is set by the C command, but stepping does not begin with this
command. The continuous mode may also be selected by external signal. This is done by
forcing the SLEW signal low as the CY545 starts stepping.
© 2002 Cybernetic Micro Systems
19
Chapter 5 - Motor Control Commands
ETC [ ETC ]
